/*
 * Created on 21-Jan-2005
 * Created by Paul Gardner
 * Copyright (C) Azureus Software, Inc, All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 */

package com.aelitis.azureus.core.dht.transport.udp.impl;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.InetSocketAddress;

import org.gudy.azureus2.core3.util.SystemTime;

import com.aelitis.azureus.core.dht.DHT;
import com.aelitis.azureus.core.dht.transport.DHTTransportException;
import com.aelitis.azureus.core.dht.transport.udp.DHTTransportUDP;
import com.aelitis.azureus.core.dht.transport.udp.impl.packethandler.DHTUDPPacketNetworkHandler;
import com.aelitis.net.udp.uc.PRUDPPacketRequest;

/**
 * @author parg
 * 
 */

public class DHTUDPPacketRequest extends PRUDPPacketRequest implements DHTUDPPacket {
    public static final int DHT_HEADER_SIZE = PRUDPPacketRequest.PR_HEADER_SIZE + 1 + // protocol version
            1 + // originator version
            4 + // network
            4 + // instance id
            8 + // time
            DHTUDPUtils.INETSOCKETADDRESS_IPV4_SIZE + 1 + // flags
            1; // flags2

    private DHTTransportUDPImpl transport;

    private byte protocol_version;
    private byte vendor_id = DHTTransportUDP.VENDOR_ID_NONE;
    private int network;

    private byte originator_version;
    private long originator_time;
    private InetSocketAddress originator_address;
    private int originator_instance_id;
    private byte flags;
    private byte flags2;

    private long skew;

    public DHTUDPPacketRequest(DHTTransportUDPImpl _transport, int _type, long _connection_id, DHTTransportUDPContactImpl _local_contact,
            DHTTransportUDPContactImpl _remote_contact) {
        super(_type, _connection_id);

        transport = _transport;

        // serialisation constructor

        protocol_version = _remote_contact.getProtocolVersion();

        // System.out.println( "request to " + _remote_contact.getAddress() + ", proto=" + protocol_version );

        // the target might be at a higher protocol version that us, so trim back if necessary
        // as we obviously can't talk a higher version than what we are!

        if (protocol_version > _transport.getProtocolVersion()) {

            protocol_version = _transport.getProtocolVersion();
        }

        originator_address = _local_contact.getExternalAddress();
        originator_instance_id = _local_contact.getInstanceID();
        originator_time = SystemTime.getCurrentTime();

        flags = transport.getGenericFlags();
        flags2 = transport.getGenericFlags2();
    }

    protected DHTUDPPacketRequest(DHTUDPPacketNetworkHandler network_handler, DataInputStream is, int type, long con_id, int trans_id)

    throws IOException {
        super(type, con_id, trans_id);

        // deserialisation constructor

        protocol_version = is.readByte();

        // System.out.println( "request received prot=" + protocol_version );

        if (protocol_version >= DHTTransportUDP.PROTOCOL_VERSION_VENDOR_ID) {

            vendor_id = is.readByte();
        }

        if (protocol_version >= DHTTransportUDP.PROTOCOL_VERSION_NETWORKS) {

            network = is.readInt();
        }

        if (protocol_version < (network == DHT.NW_CVS ? DHTTransportUDP.PROTOCOL_VERSION_MIN_CVS : DHTTransportUDP.PROTOCOL_VERSION_MIN)) {

            throw (DHTUDPUtils.INVALID_PROTOCOL_VERSION_EXCEPTION);
        }

        // we can only get the correct transport after decoding the network...

        transport = network_handler.getTransport(this);

        if (protocol_version >= DHTTransportUDP.PROTOCOL_VERSION_FIX_ORIGINATOR) {

            originator_version = is.readByte();

        } else {

            // this should be set correctly in the post-deserialise code, however default
            // it for now

            originator_version = protocol_version;
        }

        originator_address = DHTUDPUtils.deserialiseAddress(is);

        originator_instance_id = is.readInt();

        originator_time = is.readLong();

        // We maintain a rough view of the clock diff between them and us,
        // times are then normalised appropriately.
        // If the skew is positive then this means our clock is ahead of their
        // clock. Thus any times they send us will need to have the skew added in
        // so that they're correct relative to us.
        // For example: X has clock = 01:00, they create a value that expires at
        // X+8 hours 09:00. They send X to us. Our clock is an hour ahead (skew=+1hr)
        // We receive it at 02:00 (our time) and therefore time it out an hour early.
        // We therefore need to adjust the creation time to be 02:00.

        // Likewise, when we return a time to a caller we need to adjust by - skew to
        // put the time into their frame of reference.

        skew = SystemTime.getCurrentTime() - originator_time;

        transport.recordSkew(originator_address, skew);

        if (protocol_version >= DHTTransportUDP.PROTOCOL_VERSION_PACKET_FLAGS) {

            flags = is.readByte();
        }

        if (protocol_version >= DHTTransportUDP.PROTOCOL_VERSION_PACKET_FLAGS2) {

            flags2 = is.readByte();
        }
    }

    protected void postDeserialise(DataInputStream is)

    throws IOException {
        if (protocol_version < DHTTransportUDP.PROTOCOL_VERSION_FIX_ORIGINATOR) {

            if (is.available() > 0) {

                originator_version = is.readByte();

            } else {

                originator_version = protocol_version;
            }

            // if the originator is a higher version than us then we can't do anything sensible
            // working at their version (e.g. we can't reply to them using that version).
            // Therefore trim their perceived version back to something we can deal with

            if (originator_version > getTransport().getProtocolVersion()) {

                originator_version = getTransport().getProtocolVersion();
            }
        }
    }

    public void serialise(DataOutputStream os)

    throws IOException {
        super.serialise(os);

        // add to this and you need to amend HEADER_SIZE above

        os.writeByte(protocol_version);

        if (protocol_version >= DHTTransportUDP.PROTOCOL_VERSION_VENDOR_ID) {

            os.writeByte(DHTTransportUDP.VENDOR_ID_ME);
        }

        if (protocol_version >= DHTTransportUDP.PROTOCOL_VERSION_NETWORKS) {

            os.writeInt(network);
        }

        if (protocol_version >= DHTTransportUDP.PROTOCOL_VERSION_FIX_ORIGINATOR) {

            // originator version

            os.writeByte(getTransport().getProtocolVersion());
        }

        try {
            DHTUDPUtils.serialiseAddress(os, originator_address);

        } catch (DHTTransportException e) {

            throw (new IOException(e.getMessage()));
        }

        os.writeInt(originator_instance_id);

        os.writeLong(originator_time);

        if (protocol_version >= DHTTransportUDP.PROTOCOL_VERSION_PACKET_FLAGS) {

            os.writeByte(flags);
        }

        if (protocol_version >= DHTTransportUDP.PROTOCOL_VERSION_PACKET_FLAGS2) {

            os.writeByte(flags2);
        }
    }

    protected void postSerialise(DataOutputStream os)

    throws IOException {
        if (protocol_version < DHTTransportUDP.PROTOCOL_VERSION_FIX_ORIGINATOR) {

            // originator version is at tail so it works with older versions

            os.writeByte(getTransport().getProtocolVersion());
        }
    }

    public DHTTransportUDPImpl getTransport() {
        return (transport);
    }

    protected long getClockSkew() {
        return (skew);
    }

    public byte getProtocolVersion() {
        return (protocol_version);
    }

    protected byte getVendorID() {
        return (vendor_id);
    }

    public int getNetwork() {
        return (network);
    }

    public void setNetwork(int _network) {
        network = _network;
    }

    public byte getGenericFlags() {
        return (flags);
    }

    public byte getGenericFlags2() {
        return (flags2);
    }

    protected byte getOriginatorVersion() {
        return (originator_version);
    }

    protected InetSocketAddress getOriginatorAddress() {
        return (originator_address);
    }

    protected void setOriginatorAddress(InetSocketAddress address) {
        originator_address = address;
    }

    protected int getOriginatorInstanceID() {
        return (originator_instance_id);
    }

    public String getString() {
        return (super.getString() + ",[prot=" + protocol_version + ",ven=" + vendor_id + ",net=" + network + ",ov=" + originator_version + ",fl="
                + flags + "/" + flags2 + "]");
    }
}
